When I first got my 2007 1500 5.7L I could get 22 MPG on highway and was getting 17 MPG city now it is 15 MPG straight.

What are the potential problems? Not sure if the MDS is working - What would stop the switch over?

 

When you first got it, you probably babied the gas and things change after a while, especially when you get comfortable in a vehicle!

Stop reading the overhead and calculate it yourself. No Hemi, not even a 2wd is gonna get 22mpg or else Dodge would vbe advertising it all the time to beat out the competition! I think when I was going downhill one time I reset the overhead and it read 46mpg because I was at idle going down a 20% grade on the highway not touching the gas.
I get 15 myself just like most Hemi owners. I turned the MDS off, altered my shift points and maintained almost the same gas mileage as stock with a Superchip tuner, but don't buy a tuner to save on gas. To save on gas you need to buy a car and sell your truck. My truck's sticker says 13/17 and it's a '08 QC 4wd w/MDS.

It's getting colder and winter blend gas is out so maybe that could be another reason.
Plugs are due every 30kmi so depending on how many miles you have...they could be due. I don't see plugs eating up anymore than 1mpg though especially if your truck runs smooth...

 

Thanks - most likely I babied it / good to know what I am getting is standard.

I probably need to change the plugs and air filter. The only thing I have changed regularly has been the oil and oil filter.

Thanks again
Charles

 

Newton,

I agree with what Rich says above. Many different possibilities.

 

How many miles are on the spark plugs? I changed mine at 100,000 miles (i know, i know, it was way over due) and that gained me 3mpg. The rest could be environment changes, fuel, air filter, tires, a ton of other things.